I need to add a limit switch to an existing lift system that limits up and down travel. It’s a simple winch system with a corded control. We’re having trouble with inexperienced individuals running the system too far, up or down, and it rat nests the cables. How would I go about doing this? It would save us hours of headache. Thanks for your help.

I've gone and made an attempt at building a height adjustable table (think ironing board). Originally I was going to use stainless steel for the pipe, but after finding out that it would more than quadruple the price, I ended up with SCH40 Aluminum. I used three 48" long, 1" ID pipe for the legs which criss-cross and attached them to two 36" long, 1.25" ID feet.

I put it all together and mocked up a table top and everything works great.... Then I added some weight to it do simulate the weight of the actual top I plan to use (70lbs) and the pipes start to flex and it makes the whole thing kind of springy. If you set a glass of water on top you can see the water moving back and forth as the table bounces (jiggles?) until it finally settles and stops.

I'd attach pictures, but I don't see that option. Here's a link to a video that has a similar table design and operation.
---removed---

Is there any way to stiffen this thing up enough to make it more solid? I thought about drilling into the long pipes and filling them with concrete, but what happens when that starts to crack? I also thought of cutting the welds and inserting 1" solid steel rod (or flat steel oriented vertically) into the pipes. Or there's always the option to add pipe.

Would any of these options work? Any other ideas? Or am I out $100 and need to redo this with larger diameter steel?

]]>Mechanical Engineering Forummediaviewcon1https://www.engineersedge.com/engineering-forum/showthread.php/5587-How-to-calculate-flexural-yield-strengthRivet related question, how many and what size?https://www.engineersedge.com/engineering-forum/showthread.php/5585-Rivet-related-question-how-many-and-what-size?goto=newpost
Tue, 21 May 2019 07:18:10 GMT

I'm replacing the floor of an all aluminum trailer (7'x13') as part of a camper conversion. I will be using 11 gauge (0.12") 6000 series aluminum and the trailer floor beams are currently 24" centres (mix of tubing and i-beam) but I'm planning on welding in some 3/8" x 1.5" aluminum angle between the existing beams to shorten that span to under 12 inches.

Loads will be human weight at most in any given sqft with the worst case being say a piggy back with feet closely together so let's say max load ever under 300 pounds in any given square foot.

My question is, what size rivets and what type of either pattern or spacing? My plan was/is to use 120 degree countersink 3/16th aluminum blind rivets with a stainless mandrel but I will adjust as needed.

Some areas (back fold down door for example) will also have a second layer of thin 20 gauge-ish) diamond plate on top of the 11 gauge so I'm not sure if that impacts things.

Hello! Student in engineering. I just saw an autocad drawing that confused me. Coordinates were listed as "N. 2+200" for example, but then coordinates within the grid (for the design) were in x and y coordinates. Can someone help explain what the numbers and + sign mean? Does this have something to do with a specific way to write northings and eastings coordinates? Or does it have to do with station in autocad? Thank you in advance!

I have attached a sketch that is a simplified version of a slot profile I'm trying to constrain. My question is: is it properly communicated that the '8' dimension on the top view is centered around the '2' dimension because of the feature control frame reference to datum B? I put 'symmetric' in quotes in the title because, although the slot length is centered on the square cut-out, it is not symmetric about datum B due to its tilt.

Do I need to add another dimension from either end of the slot to datum B in order to constrain it in the Y-direction (relative to the top view)?

]]>whknapperhttps://www.engineersedge.com/engineering-forum/showthread.php/5582-Profile-of-a-line-implied-symmetric-constraintStatics help: Rigid body equilibriumhttps://www.engineersedge.com/engineering-forum/showthread.php/5578-Statics-help-Rigid-body-equilibrium?goto=newpost
Fri, 10 May 2019 13:35:30 GMTGot a problem that i have no idea on how to start working at. Idea is that im supposed to figure out the lenght of h with respect to b so the water...

Got a problem that i have no idea on how to start working at. Idea is that im supposed to figure out the lenght of h with respect to b so the water can flow. Any tips? Thanks in advance.

]]>General Physicstttt257https://www.engineersedge.com/engineering-forum/showthread.php/5578-Statics-help-Rigid-body-equilibriumHow to remove water from liquid digestate?https://www.engineersedge.com/engineering-forum/showthread.php/5577-How-to-remove-water-from-liquid-digestate?goto=newpost
Fri, 10 May 2019 09:21:51 GMTI am working on a project to dry liquid digestates (residue from the fermentation process of biogas plants). The aim of the project is to reduce...

I am working on a project to dry liquid digestates (residue from the fermentation process of biogas plants). The aim of the project is to reduce the volume of the liquid digestate, in order to cut the transport and storage costs for the farmers. This volume reduction is achieved by evaporation of water from the digestate.

The liquid digestate has a dry matter (DM) content of about 3%. The digestate is primarily made up of animal manure and maize silage. It is a non-newtonian fluid having a viscosity of 4 - 15 mPa-s. It exhibits a shear thinning behaviour, where the viscosity decreases with shear rate.

A drum dryer is used, which runs continuously (24x7) with an automatic setting. The dryer makes use of the heat from the combined heat and power (CHP) unit. The task is to remove/evaporate 1 liter of water for every 1 kW of heat supplied from the CHP unit.

The liquid digestate after the separation process is fed into the drum dryer at a temperature of 40°C. Hot air with a temperature of 70°C is blown into the drum to dry the digestate. The drum is packed with cooling tower fills (see image Packed fills) in order to facilitate faster drying by increasing the heat transfer surface area between digestate and air.

The problem is that the tiny fibres from the liquid digestate, inspite of pre-separation process, get deposited on the cooling tower fills and the clog the air flow (see image Fibre deposition). Thereby the whole functioning of the dryer is affected. These tiny fibres are suspended and float in the liquid digestate, as it is difficult to filter them out.

Hence, I would like to know, if heating the liquid digestate helps? What happens to these tiny floating fibres in the liquid, when the temperature is raised from 40°C to 60°C? Definitely the viscosity of the liquid would decrease, but does it affect these tiny fibres?

How can this fibre deposition and clogging of flow be avioded? Are there better methods to increase the heat transfer area, other than cooling tower fills? Any new suggestions are welcome.

]]>Mechanical Engineering Forumchen_tockhttps://www.engineersedge.com/engineering-forum/showthread.php/5577-How-to-remove-water-from-liquid-digestatehelp to estimate the pulling force in this pulley-cable arrangementhttps://www.engineersedge.com/engineering-forum/showthread.php/5576-help-to-estimate-the-pulling-force-in-this-pulley-cable-arrangement?goto=newpost
Thu, 09 May 2019 08:22:12 GMTDear all,
Can you help me estimate the *pulling force or tension* in the cable please ...
Please see the attached image.
Since it is a...

Dear all,

Can you help me estimate the pulling force or tension in the cable please ...
Please see the attached image.

Since it is a single cable from beginning to end, is there any mechanical advantage at all ??

]]>Engineering and Design Main Forum | Engineers Edge Forumsnaveenbnchttps://www.engineersedge.com/engineering-forum/showthread.php/5576-help-to-estimate-the-pulling-force-in-this-pulley-cable-arrangementFamiliar with HEC-RAS? (related to Water Resources Management and Engineering)https://www.engineersedge.com/engineering-forum/showthread.php/5570-Familiar-with-HEC-RAS-%28related-to-Water-Resources-Management-and-Engineering%29?goto=newpost
Thu, 02 May 2019 07:44:00 GMTGreetings, everyone! :)
I am currently taking Water Resources Management under BS Civil Engineering program, and we are taught to use HEC-RAS to...

Greetings, everyone! :)

I am currently taking Water Resources Management under BS Civil Engineering program, and we are taught to use HEC-RAS to run river flow simulations for various river set-ups and characteristics (steady, unsteady, etc). The software is pretty much straightforward and I am having fun learning how to use all of its tools.

However, one tricky part is analyzing data inputs. Our professor gave us some clear instructions for the first few river flow problems, but I am clueless about this latest one. I assume this one is taken out of some file type that the software can read directly. Unfortunately, this is all I have and I just need to know what the symbols and numbers mean. Can someone here help me out to identify what these figures mean?

For the second part, I already distinguished FS, MS, CS, and VCS as the soil texture classifications, but I have no idea what the other numbers mean.

I'd really appreciate anyone who can guide me here. Once I know what these values stand for, I can easily proceed with running the simulation. Thank you so much in advance, and I hope to learn more about the experts from here! :)

]]>jmrsalongahttps://www.engineersedge.com/engineering-forum/showthread.php/5570-Familiar-with-HEC-RAS-%28related-to-Water-Resources-Management-and-Engineering%29Ab Toning Systemshttps://www.engineersedge.com/engineering-forum/showthread.php/5569-Ab-Toning-Systems?goto=newpost
Wed, 01 May 2019 06:00:28 GMTWhat material is likely to have been used on the back of the Ab Toning System in the link below, that allows it to stick to skin strongly?
...

What material is likely to have been used on the back of the Ab Toning System in the link below, that allows it to stick to skin strongly?

]]>Engineering and Design Main Forum | Engineers Edge Forumsbenjamin_bankshttps://www.engineersedge.com/engineering-forum/showthread.php/5568-Low-Friction-FabricsHow a Tensil Stress Strain Curve Is Createdhttps://www.engineersedge.com/engineering-forum/showthread.php/5567-How-a-Tensil-Stress-Strain-Curve-Is-Created?goto=newpost
Sun, 28 Apr 2019 20:04:51 GMTHello all
I was hoping someone could help me interpreting a Stress Strain Curve.
As part of my introduction to Civil Engineering I am trying to...

Hello all

I was hoping someone could help me interpreting a Stress Strain Curve.

As part of my introduction to Civil Engineering I am trying to get my head around how a stress strain curve is created, for example I have a steel sample and wish to perform a tensile test.

While the steel sample is being stretched I want to know: -

Does the force applied to the steel sample continue to increase until the steel sample elongates at which point no additional load is applied until the steel stops elongating at which point more force is applied until the steel continues to elongate?

Or

Does the force applied to the steel sample continue to increase uniformly and the elongation measured at regular intervals?

Does this make sense?

Thank you.

]]>christian Bendishttps://www.engineersedge.com/engineering-forum/showthread.php/5567-How-a-Tensil-Stress-Strain-Curve-Is-CreatedLooking for assistance with a Wind Load Calculationhttps://www.engineersedge.com/engineering-forum/showthread.php/5566-Looking-for-assistance-with-a-Wind-Load-Calculation?goto=newpost
Sun, 28 Apr 2019 05:38:42 GMTHello,
Im hopeful that this is the right place to post such a question. We are at Witts end trying to find anyone to help us with this calculation....

Hello,
Im hopeful that this is the right place to post such a question. We are at Witts end trying to find anyone to help us with this calculation.

We are a Los Angeles testing company looking for assistance with a wind load calculation. The calculation is based on the ASCE/SEI 7-05. As water intrusion testers, we are attempting to recreate a leak within a fenestration product based on historical data i.e. wind pressure. We accomplish this with the use of a negative air chamber on the interior side of the fenestration product.

Finding the correct pressure for a specific day / time in history to re create the leak conditions is where we are lost.

Our standard is the AAMA 511-08 essentially a Forensic test of the window.

We have located the historical wind speed for the dates when the windows were know to have leaked and averaged them out. That number is 5.8mph

We'd really like to know how to do the equation as opposed to just getting an answer.

Ive attached the section of the AAMA standard which references our test procedure and how the calc is to be conducted.

If the portion of the standard which we attached is not enough info, there are a few more pages we can also attach.